3/12 Photosynthesis1. Does making a chemical bond

require or release energy?2. Does turning ATP into ADP

require or release energy?

Make sure your Test+ has your name on it if it’s not stapled. Turn BOTH your Test+ and

your Test into the class inbox.

Homework For next time, read and take notes on

p. 105-111, and on p. 340-347.

I will check your book notes next time. Bring all that you’ve taken.

Glucose Glucose = simple carbohydrate.

Carbohydrates are the last of our four macromolecules.

You must know glucose’s chemical symbol:

C6H12O6 Six carbons, twelve hydrogens, six

oxygens.

Glucose

Food for life! C6H12O6

Glucose

C_H_O_

Glucose

Checkpoint What’s the chemical that is a cell’s food, that

stores large amounts of energy? What’s the chemical that is a cell’s little battery,

quickly storing small amounts of energy? How do you get that little battery to release

energy? How do you “recharge” it and use it to store

energy again? What is the chemical formula for the large

battery?

Autotrophs Energy enters the web of living things

through the autotrophs, so we’ll start with them.

Autotrophs make their own food (glucose). The #1 method that autotrophs on Earth do this is through photosynthesis. Photo means light. What did synthesis

mean again?

Photosynthesis Photosynthesis = use sunlight energy

to make food.

Photosynthesis We know we will wind up with glucose (food),

and we know light energy makes it happen. What else goes on?

Atoms are never created or destroyed, just recycled. So the carbons, hydrogens, and oxygens in glucose must come from somewhere.

_____ + _____ --> _____ + C6H12O6

Photosynthesis Summary of photosynthesis! KNOW THIS.

6CO2 + 6H2O --light--> 6O2 + C6H12O6

The autotroph uses up carbon dioxide and water to store the sunlight energy in glucose. It releases oxygen as leftovers, a waste product.

Photosynthesis Say it again.

_CO2 + _H2O --light--> _O2 + C6H12O6

Photosynthesis

Say it again.

_ ____ + _ ____ --light--> _O2 + C6H12O6

Photosynthesis

Say it again.

_ ____ + _ ____ ----> _ ___ + ______

Photosynthesis So, photosynthesis is capturing energy

from sunlight and storing it in glucose. Two parts to this. Capturing energy from

sunlight, and making glucose.

Photosynthesis The Light Reactions capture sunlight energy

and store it in ATP and NADPH (it’s another “battery” we’ll learn in a moment.)

The Calvin Cycle uses that captured energy to make glucose. The Calvin Cycle is also called the Light-Independent Reactions, or Dark Reactions.

Light Reactions In chloroplast thylakoid. 1. Light hits pigments, making their electrons

get excited and “bounce out of orbit.” 2. Water (H2O) is broken down into hydrogen

(H+) and 2 oxygens, the oxygens are released as waste.

3. The energy in the excited electrons and the H+ is used to “charge” an ATP battery (turning ADP into ATP), and to charge a battery in a similar way (turning NADP+ into NADPH).

Light Reactions The pigments that are involved in

photosynthesis absorb red light very well, and some blue light. Red and blue light turn out to be good at exciting the pigment’s electrons.

White light (like sunlight) contains all colors of light.

Infer! What does this have to do with the color of most plant leaves?

Light Reactions So:

Sunlight energy H2O split into H+ and O2 (waste) ADP energized into ATP, and NADP+ energized into NADPH

http://www.johnkyrk.com/photosynthesis.html http://www.stolaf.edu/people/giannini/flashanimat/

metabolism/photosynthesis.swf (More detailed than you need to know but shows what a “chain reaction” is going on)

The cell will then use the energy now stored in ATP and NADPH to make glucose in the Calvin cycle…

Calvin Cycle (“Dark Reaction”)

The Calvin Cycle uses energy from ATP and NADPH (from the Light Reactions) to turn CO2 and H+ into glucose.

In chloroplast stroma.

ATP and NADPH are the batteries. 6 CO2 from the atmosphere are turned into two 3-carbon molecules, which will then be turned into one 6-carbon molecule, glucose.

Using energy from ATP and NADPH means they turn back into ADP and NADP+, and are recycled back into the Light Reactions to be recharged.

Calvin Cycle http://www.sinauer.com/cooper/4e/ani

mations0305.html (Again, more complicated than you must know, but shows cyclic nature)

Photosynthesis And that’s it! The overall equation is

that the plant uses sunlight as the energy to power turning CO2 and H2O into O2 and C6H12O6, but that’s just the sum total, each individual step doesn’t do that whole thing.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Photosynthesis Each person should make a flowchart, though

it’s good to talk to each other. Describe the process of photosynthesis from

start to finish. You can illustrate it, like a cartoon or with symbols, or you can just use words.

If you are confused, find somebody who is less

confused and ask them to explain. If you are less confused, trust me, it helps to

“teach” it to somebody!